1. Field of the Invention
The present invention relates to a wavelength conversion method and a wavelength converter for outputting light having a wavelength different from that of an input light.
2. Related Background Art
A wavelength converter used in an optical communication network converts input signal light into signal light having a wavelength different from the wavelength of, but carrying the same information as, the input signal light, and outputs the converted signal light (e.g., PCT Laid-Open Pamphlet WO 99/10770, PCT Japanese Patent Application Publication No. 2002-514322, and Japanese Patent Application Publication No. 2002-296630). In a known wavelength converter, temporally amplitude-modulated input signal light and continuous light having larger power than the input signal light are multiplexed and propagated through an optical fiber so that output signal light having a wavelength different from the wavelength of the input signal light is generated by a non-linear optical phenomenon caused with such propagation, and is output.
In the known wavelength converter, continuous light is employed as pump light to cause the non-linear optical phenomenon in an optical fiber, and the larger the power of the continuous light, the better. However, since the continuous light has a narrow spectral line width of wavelength and has a low Stimulated Brillouin Scattering (SBS) threshold, the Brillouin scattering is more apt to occur, and the continuous light has a limit in power capable of being input to the optical fiber. As a result, there is also a limit in the power of output signal light obtained by the wavelength conversion.
For avoiding the occurrence of Brillouin scattering, there are known methods such as phase-modulating or dithering of the continuous light which is the pump light. However, solution by such methods needs a large-sized wavelength converter and results in increase of cost.